An elephant’s trunk has 40,000 muscles and weighs more than a Burmese python. The attachment is strong enough to uproot a tree, but strong enough to absorb fragile tortilla chips.
But how does an elephant’s brain help to accomplish these works of art? This has been difficult to study, says Michael Brecht, a neuroscientist at Humboldt University in Berlin. An elephant’s brain, which weighs more than 10 kilograms, collapses quickly after death and is difficult to store. “I tend to think that the big animals are a little neglected because we don’t do enough work on big brains,” Dr. Brech said.
Dr. Brecht and his colleagues were lucky enough to find the brains of elephants that had died of natural causes or of health reasons and had them either frozen or processed in the Leibniz Institute of Zoology and Wildlife. Research in Berlin.
In a study published Wednesday in the journal Science Advances, Dr. Brecht and colleagues report that elephants have more facial neurons than any other mammal, contributing to trunk agility and other bodily abilities. The study helped identify major differences between the neural wiring of African savannah elephants and Asian elephants.
Using the brains of four Asian elephants and four African savannah elephants, the researchers identified the frontal nucleus, a cluster of neurons located in the brainstem and connected to the facial nerves. In mammals, these neurons serve as the control center for the muscles of the face. They are a command when you wrinkle your nose, purse your lips or raise your eyebrows. They help elephants hire their trunks.
The researchers dissected the neurons that control the elephants’ ears, lips and trunk in the frontal cortex. African elephants sported 63,000 facial neurons, while their Asian relatives had 54,000. The only mammals that have more are dolphins, packing about 90,000 facial nerve cells into their sensitive noses.
While his team expected both African savannah and Asian elephants to have large stores of facial neurons, Dr. Brecht said the differences between the two species were interesting.
Although the animals look similar, they have different facial features. African elephants have very large ears, which they shake when charging. The researchers found a neurological link – African elephants have about 12,000 facial nerves that control their ears alone. That’s not only the number of neurons that control the ears of Asian elephants, but nearly 3,000 more neurons than are needed to make the entire human face.
Another big difference is how each elephant holds its trunk, which requires about half of an elephant’s total facial neurons to function. African elephants use two finger-like projections on the tips of their trunks to pinch objects, similar to a pair of chopsticks. Asian elephants have a finger-like projection and carry their belongings around their trunks. The researchers identified two neural regions in African elephants, which are probably associated with finger control at the tip of their trunks. Those regions are underrepresented in Asian elephants.
Describing the role of different parts of the elephant’s frontal nucleus accumbens network, Vanderbilt University neuroscientist Susanna Herculano-Hauzel, who was not involved in the new study, thinks the number of neurons is not surprising for such a mammal. .
Other parts of the elephant brain are also fascinating, she says. Dr. Herculano-Hauzel’s research has shown that the elephant’s cerebellum, the part of the brain that controls motor functions, is 12 times larger than expected for a mammal of its size. “The elephant’s cerebellum is also stratospheric compared to other mammals,” she says.
While facial nerves may not be off the charts by comparison, Dr. Brecht’s better understanding of elephants’ structures provides insight into other large mammals — including humans.
“Even though we’re not as big as an elephant, we’re still pretty big,” he said.